The invention relates to an oxygen breathing device, in particular for cockpit crew member of an aircraft, comprising:                a pressurized oxygen source for storing pressurized oxygen,        an oxygen mask, adapted to fit to nose and mouth of a person to be supplied with oxygen from the pressurized oxygen source,        an oxygen supply line connecting the pressurized oxygen source with the oxygen mask,        a pressure regulator/safety valve coupled in the oxygen supply line to selectively open or shut off oxygen flow from the pressurized oxygen source to the oxygen mask and/or to control pressure of said oxygen supplied to the oxygen mask.        
A further aspect of the invention is a method for providing oxygen to a passenger or crew member of an aircraft.
Oxygen breathing devices of the aforementioned type are used to provide oxygen to a crew member or passenger in an emergency situation. A particular application of oxygen breathing devices is the supply of oxygen to a crew member in a cockpit of an aircraft. In such applications of oxygen breathing devices in a cockpit use it is known to provide an oxygen source like a pressurized oxygen in a tank and to provide oxygen from such source to the cockpit member in an emergency situation.
To make sure that the oxygen breathing device is in proper condition to provide oxygen to the pilot it is required and prescribed to perform a pre-flight check of the oxygen breathing device. In such pre-flight check in particular the valves and the breathing mask worn by the pilot are checked for proper function by providing oxygen from the oxygen source.
Such pre-flight check is performed before each flight of an aircraft and after a certain number of pre-flight checks it is required to replace the pressurized oxygen source since the oxygen stored therein is no longer sufficient to provide oxygen for a period of time corresponding to an emergency situation. Thus, a first drawback of such existing oxygen breathing devices is the need to frequently replace the pressurized oxygen source, thus producing enhanced costs in the maintenance of the whole oxygen breathing device.
Still further, in existing oxygen breathing devices it is required to permanently provide pressurized oxygen to a valve member which can be activated to perform pre-flight check or in an emergency situation. However, a small amount of oxygen may flow through such a valve, thus resulting in a permanent loss of oxygen to a small amount. This permanent loss will slowly reduce the volume of oxygen stored in the pressurized oxygen source and thus will further require replacement of the pressurized oxygen source after a certain period of time, even if no pre-flight check has been performed.
Still further, while it is usually preferred to provide oxygen to crew member or passenger in emergency situations like a decompression of the aircraft, it is less preferable to provide oxygen in emergency situations like smoke or fire in the cockpit or aircraft. In such situations, the use of oxygen will increase the risk of burn injuries to the face of the crew member or passenger using the oxygen breathing device due to an increased concentration of oxygen in the area surrounding the face of the crew member or passenger. Thus, there is a need for an oxygen breathing device reducing the risk of burn injuries of the crew member or passenger using the device.